//
// (C) Copyright 2009 Irantha Suwandarathna (irantha@gmail.com)
// All rights reserved.
//

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use _in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions _in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer _in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


using System;
using System.Collections.Generic;
using EffiProz.Core.Rights;
using EffiProz.Core.Lib;


namespace EffiProz.Core
{

    /**
     * Container that maintains a map of session id's to Session objects.
     * Responsible for managing opening and closing of sessions.
     *
     * @author fredt@users
     * @version 1.8.0
     * @since 1.7.2
     */
    public class SessionManager
    {

        int sessionIdCount = 1;
        private LongKeyHashMap sessionMap = new LongKeyHashMap();
        private Session sysSession;
        private Session sysLobSession;

        // TODO:
        //
        // Eliminate the Database-centric nature of SessionManager.
        // e.g. Sessions should be able to migrate from one Database instance
        // to another using session control language moderated by
        // SessionManager

        /**
         * Constructs an new SessionManager handling the specified Database.
         * Creates a SYS User.
         */
        public SessionManager(Database db)
        {

            User sysUser = db.getUserManager().getSysUser();

            sysSession = new Session(db, sysUser, false, false, sessionIdCount++,
                                null, 0);
            sysLobSession = new Session(db, sysUser, true, false,
                                        sessionIdCount++, null, 0);
        }

        // TODO:
        //
        // It should be possible to create an initially 'disconnected' Session that
        // can execute general commands using a SessionCommandInterpreter.
        //
        // EXAMPLES: Open a Session to start a Server, add/remove
        //           databases hosted by an existing Server, connect to a
        //           Database...
        //
        // REQUIRES:  auth scheme independent of any particular Database instance
        //            e.g. provide service to use /etc/passwd and /etc/groups,
        //                 JAAS-plugin, etc.

        /**
         *  Binds the specified Session object into this SessionManager's active
         *  Session registry. This method is typically called internally from
         * {@link
         *  Database#connect(String,String) Database.connect(username,password)}
         *  as the const step, when a successful connection has been made.
         *
         * @param db the database to which the new Session is initially connected
         * @param user the initial Session User
         * @param _readonly the initial ReadOnly attribute for the new Session
         */
        public Session newSession(Database db, User user,
                                           bool _readonly, bool forLog,
                                           String zoneString,
                                           int timeZoneSeconds)
        {
            Session s = new Session(db, user, !forLog, _readonly, sessionIdCount,
                               zoneString, timeZoneSeconds);

            s._isProcessingLog = forLog;
            sessionMap.put(sessionIdCount, s);
            sessionIdCount++;

            return s;
        }
        /**
    * Retrieves a new SYS Session.
    */
        public Session getSysSessionForScript(Database db)
        {

            Session session = new Session(db, db.getUserManager().getSysUser(),
                                          false, false, 0, null, 0);

            session._isProcessingScript = true;

            return session;
        }

        public Session getSysLobSession()
        {
            return sysLobSession;
        }

        /**
         * Retrieves the special SYS Session.
         *
         * @return the special SYS Session
         */
        public Session getSysSession(string schema,
                                     bool forScript)
        {

            sysSession.currentSchema =
                sysSession.database.schemaManager.getDefaultSchemaHsqlName();
            sysSession._isProcessingScript = forScript;
            sysSession._isProcessingLog = false;

            sysSession.setUser(sysSession.database.getUserManager().getSysUser());

            return sysSession;
        }

        /**
         * Retrieves the special SYS Session.
         *
         * @return the special SYS Session
         */
        public Session getSysSession()
        {

            sysSession.currentSchema =
                sysSession.database.schemaManager.getDefaultSchemaHsqlName();
            sysSession._isProcessingScript = false;
            sysSession._isProcessingLog = false;

            sysSession.setUser(sysSession.database.getUserManager().getSysUser());

            return sysSession;
        }

       
/**
 * Retrieves the common SYS Session.
 */
        public Session getSysSession(String schema, User user)
        {

            sysSession.currentSchema =
                sysSession.database.schemaManager.getSchemaHsqlName(schema);
            sysSession._isProcessingScript = false;
            sysSession._isProcessingLog = false;

            sysSession.setUser(user);

            return sysSession;
        }

        public Session newSysSession(QNameManager.QName schema, User user)
        {

            Session session = new Session(sysSession.database, user, false, false,
                                          0, null, 0);

            session.currentSchema = schema;

            return session;
        }

        /** @todo sig change should be either:  closeAllSessions(Database) or closeAllSessions(dbID) */

        /**
         * Closes all Sessions registered with this SessionManager.
         */
        public void closeAllSessions()
        {
            lock (this)
            {
                // don't disconnect system user; need it to save database
                Session[] sessions = getAllSessions();

                for (int i = 0; i < sessions.Length; i++)
                {
                    sessions[i].close();
                }
            }
        }

        /**
         *  Removes the session from management and disconnects.
         *
         * @param  session to disconnect
         */
        public void removeSession(Session session)
        {
            lock (this)
            {
                sessionMap.remove(session.getId());
            }
        }

        /**
         * Removes all Sessions registered with this SessionManager.
         */
        public void clearAll()
        {
            lock (this)
            {
                sessionMap.clear();
            }
        }

        /**
         * Returns true if no session exists beyond the sys session.
         */
        public bool isEmpty()
        {
            lock (this)
            {
                return sessionMap.isEmpty();
            }
        }

        /**
         * Retrieves a list of the Sessions _in this container that
         * are visible to the specified Session, given the access rights of
         * the Session User.
         *
         * @param session The Session determining visibility
         * @return the Sessions visible to the specified Session
         */
        public Session[] getVisibleSessions(Session session)
        {
            lock (this)
            {
                return session.isAdmin() ? getAllSessions()
                                         : new Session[] { session };
            }
        }

        /**
         * Retrieves the Session with the specified Session identifier or null
         * if no such Session is registered with this SessionManager.
         */
        public Session getSession(long id)
        {
            lock (this)
            {
                return (Session)sessionMap.get(id);

            }
        }

        public Session[] getAllSessions()
        {
            lock (this)
            {
                Session[] sessions = new Session[sessionMap.size()];
                Iterator it = sessionMap.values().iterator();

                for (int i = 0; it.hasNext(); i++)
                {
                    sessions[i] = (Session)it.next();
                }

                return sessions;
            }
        }

        public bool isUserActive(string userName)
        {
            lock (this)
            {
                Iterator it = sessionMap.values().iterator();

                for (int i = 0; it.hasNext(); i++)
                {
                    Session session = (Session)it.next();

                    if (userName.Equals(session.getUser().getNameString()))
                    {
                        return true;
                    }
                }

                return false;
            }
        }

        public void removeSchemaReference(Schema schema)
        {
            lock (this)
            {
                Iterator it = sessionMap.values().iterator();

                for (int i = 0; it.hasNext(); i++)
                {
                    Session session = (Session)it.next();

                    if (session.getCurrentSchemaHsqlName() == schema.name)
                    {
                        session.resetSchema();
                    }
                }
            }
        }

        public void resetLoggedSchemas()
        {
            lock (this)
            {
                Iterator it = sessionMap.values().iterator();

                for (int i = 0; it.hasNext(); i++)
                {
                    Session session = (Session)it.next();

                    session.loggedSchema = null;
                }
            }
        }
    }
}